import java.net.*;
import java.io.*;
import java.util.*;

public class CompList {

    public static void main(String[] args) {
	ServerSocket serverSocket = null;
	int portNr = 4444;
	try {
	    // Loome uue soketi, mis kuulab localhosti 4444 pordis
	    serverSocket = new ServerSocket(portNr);
	} catch (IOException e) {
	    System.err.println(e);
	    e.printStackTrace(System.err);
	    // kui socketi loomine ebaõnnestus, siis lõpetame programmi töö
	    System.exit(1);
	}
	// computers sisaldab kõikide nende arvutite IP aadresse, 
	// mis on selle programmi poole pöördunud
	Set computers = new HashSet();
	while (true) {
	    try {
		Socket s = serverSocket.accept();
		InetAddress ip = s.getInetAddress();
		computers.add(ip);
	    } catch (IOException e) {
		System.err.println(e);
		e.printStackTrace(System.err);
		continue;
	    }
	    System.out.println("--------------------");
	    System.out.println("Serveri poole on pöördutud järgmistest arvutitest:");
	    Iterator it = computers.iterator();
	    while(it.hasNext()) {
		InetAddress ip = (InetAddress) it.next();
		System.out.println("IP="+ip.getHostAddress() +
				" hostname="+ip.getHostName());
	    }
	    System.out.println("--------------------");
	}
    }

}